In recent years, with the development of laws concerning the storage of information, such as electronic documents act and SOX act (Sarbanes-Oxley Act), and with the development of ILM (Information Lifecycle Management), the demand for a long-term storage of information has increased explosively. To meet such a demand, development of an information recording medium and an information recording and reproducing apparatus that have a large capacity, high reliability, and low cost has been desired.
Conventionally, for such a long-term storage of information, information recording and reproducing apparatuses using optical disks such as a low-cost DVD (Digital Versatile Disc), magnetic tapes such as a LTO (Linear Tape-Open), or the like have been used. However, the magnetic tapes such as the LTO have problems such as a slow speed of access to information recorded as well as shortness of the storage life of the information that is the most important reliability item. In recent years, there is a also a demand for a higher speed of access to the information stored in the information recording medium, for the information-recording medium and the information recording and reproducing apparatus for long-term storage so as to facilitate management of the information stored.
On the other hand, the optical disks such as a DVD meet the demand for long-term storage in terms of storage life and access speed, but has a problem of shortage of storage capacity of the optical disks serving as information recording media, for example.
Measures to solve the shortage of the storage capacity of the media mentioned above have been taken by using a film-shaped optical disk to deal with such a problem in the information recording and reproducing apparatus using the optical disk. This measures are aimed at obtaining an effect that is equivalent such that the capacity of the optical disk serving as the information-recording medium is increased. The effect is obtained such that the thickness of around 1.2 mm of the optical disks such as the DVD is reduced to around 0.1 mm-0.3 mm to obtain a film shape, thereby increasing a packing density per volume of the optical disk.
When a file-shaped optical disk having flexibility (in other words, a flexible optical disk) is used for recording and reproducing information, the information recording medium having a large storage capacity, a long storage life and a high access speed and suitable for long-term storage of information at low cost. However, the reduction in thickness of the optical disk results in lowering the rigidity in the rotation axis direction of the optical disk. Therefore, the reduction in the rigidity of the optical disk must be compensated for so as not to case any problem when the film-shaped optical disk is operated in the information recording and reproducing apparatus. Such a compensation is required particularly at the time of rotation of the optical disk and at the time of transportation of the optical disk.
When the film-shaped optical disk is directly rotated at high speed, unlike the conventional optical disk having a thickness of 1.2 mm, the surface wobbling of the optical disk increases due to the shortage of the rigidity. Therefore, it is difficult to stably obtain an excellent recording/reproducing performance. For example, as a related technology, the following method is proposed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 62-212935). In this method, a separate member having high rigidity (called a stabilization member) is installed in proximity to the film-shaped optical disk, and Bernoulli effect of airflow between the optical disk and the stabilization member is used to suppress the surface wobbling of the optical disk.
In addition, it is desirable that distance between the stabilization member and the optical disk be reduced to about 0.1 mm so that an effect to reduce the surface wobbling of the optical disk by the Bernoulli effect is provided by the above method using the stabilization member. In this case, it is highly possible that the stabilization member comes in contact with the optical disk, and damages the optical disk rises. Therefore, in this method, it is necessary to take measures to prevent the optical disk from being damaged due to the contact between the optical disk and the stabilization member. For example, as a countermeasure for preventing the optical disk from being damaged like this, Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2007-12204) discloses an effective method as follows. That is, by using the stabilization member (called a rotation stabilizing board) having a through-hole for inflow of air and having a disc shape like an optical disk, the stabilization member and the optical disk rotate together while the rotation axes thereof coincide with each other in a state where the stabilization member and the optical disk are disposed adjacent to each other.
However, the conventional stabilization member (i.e., rotation stabilizing board) having a disk shape, which is used in this method, has a prerequisite that the stabilization member is mounted as a turntable separately from the optical disk on the spindle motor provided in the optical drive serving as the information recording and reproducing apparatus. Therefore, the conventional stabilization member has drawbacks in that the structure of the optical drive is complicated, and the optical disk dedicated for the film-shaped optical disk needs to be produced, resulting in an increase in production cost of the optical drive.
In addition, it becomes a risk factor for the long-term storage of the information to use such a dedicated optical drive, in the future utilization of the information. This is because if the acquisition of the optical drive to reproduce the information stored in the optical disk becomes difficult in the future, even if the optical disk itself can be stored for a long-term, such a situation that the information that is stored for a long term cannot be utilized may occur. A use of the dedicated optical drive limits the number of optical drive manufacturers supplying the optical drives. This is disadvantageous in obtaining the optical drive in the future. Therefore, it is desirable that commercially-available optical drives mass produced for the optical disk having a thickness of 1.2 mm can be used from the viewpoint of easiness of acquisition of the optical drive in the future, instead of the optical drive dedicated for the optical disk, among the optical drives for the film-shaped flexible optical disks.
Conventionally, the rotation stabilizing board which is used in the above method has no mechanism for aligning the rotation axis of the flexible optical disk placed on the rotation stabilizing board with the rotation axis of the spindle motor. For this reason, the rotation axis of the rotation stabilizing board is sometimes greatly decentered from the rotation axis of the spindle motor, in the case of using the rotation stabilizing board. Therefore, there is a problem that it becomes difficult to record/reproduce information stably.
On the other hand, a transportation apparatus such as a changer apparatus or an accessor apparatus that transport an optical disk to an optical drive from a storage device of the optical disk is necessary when information is recorded/reproduced with respect to a plurality of optical disks in an information storage apparatus such as an optical disks library apparatus. When such a transportation apparatus transports the film-shaped flexible optical disks, it is necessary to take a measure to compensate for the reduction in rigidity of the optical disk. In other words, it is necessary to take a measure to suppress a deformation when the optical disk is transported, because the amount of deformation due to its own weight or the amount of deformation when a transportation acceleration is applied, of the optical disk of this kind is larger than them that of the optical disk having a thickness of 1.2 mm.
As conventional measures to suppress the deformation of the flexible optical disks being transported, the following methods are proposed. For example, a Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2006-268900) discloses a method of transporting an optical disk placed in a half cartridge. Patent Document 4 (Japanese Unexamined Patent Application Publication No. 2004-145995) discloses a method of transporting an optical disk being pinched by rollers. Patent Document 5 (Japanese Unexamined Patent Application Publication No. 2007-293965) discloses a method of transporting an optical disk being pinched between a sheet-like matrix and a sheet-like cover. However, these methods have a drawback that the structure of not only the transportation apparatus but also the information recording and reproducing apparatus is complicated. Therefore a simpler and easier transportation method has been desired.
[Patent Document 1]
    Japanese Unexamined Patent Application Publication No. 62-212935[Patent Document 2]    Japanese Unexamined Patent Application Publication No. 2007-12204[Patent Document 3]    Japanese Unexamined Patent Application Publication No. 2006-268900[Patent Document 4]    Japanese Unexamined Patent Application Publication No. 2004-145995[Patent Document 5]    Japanese Unexamined Patent Application Publication No. 2007-293965